The recent time witnessed a surge of interest in strong gravitational lensing by black holes is due to the Event Horizon Telescope (EHT) results, which suggest comparing the black hole lensing in both general relativity and heterotic string theory. That may help us to assess the phenomenological differences between these models. Motivated by this, we consider gravitational lensing by the nonsingular Kerr-Sen black holes, which encompass Kerr black holes as a particular case, to calculate the light deflection coefficients p and q in strong-field limits, while the former increases with increasing parameters k and charge b, later decrease. We also find a decrease in the light deflection angle α_D, angular position θ_∞ decreases more slowly and impact parameter for photon orbits u_m more quickly, but angular separation s increases more rapidly with parameters b and k. We compare our results with those for Kerr black holes, and also the formalism is applied to discuss the astrophysical consequences in the case of the supermassive black holes NGC 4649, NGC 1332, Sgr A* and M87*. In turn, we also investigate the shadows of the nonsingular Kerr-Sen black holes and show that they are smaller and more distorted than the corresponding Kerr black holes and nonsingular Kerr black holes shadows. The inferred circularity deviation Δ C≤ 0.10, for the M87* black hole shadow, put constraints on the nonsingular Kerr-Sen black hole parameters (a, k) and (a, b). The maximum shadow angular diameter for b=0.30M and k=0.30M are, respectively, θ_d=35.3461 μas and θ_d=35.3355 μas. We also estimate the parameters associated with nonsingular Kerr-Sen black holes using the shadow observables.

最近，由于事件视界望远镜（EHT）的结果，人们对黑洞强引力透镜的兴趣激增，这表明在广义相对论和杂质弦理论中比较黑洞透镜。这可能有助于我们评估这些模型之间的现象学差异。受此启发，我们考虑通过非奇异 Kerr-Sen 黑洞（包括 Kerr 黑洞）的引力透镜效应来计算强场极限下的光偏转系数 p 和 q，而前者随着参数 k 的增加而增加和费用b，以后减少。我们还发现光偏转角 α _D减小，角位置 θ _∞减小得更慢，光子轨道的影响参数 u_m更快，但角间距 s 随着参数 b 和 k 增加得更快。我们将我们的结果与克尔黑洞的结果进行比较，并应用形式主义来讨论超大质量黑洞 NGC 4649、NGC 1332、人马座 A* 和 M87* 的天体物理后果。反过来，我们还研究了非奇异 Kerr-Sen 黑洞的阴影，并表明它们比相应的 Kerr 黑洞和非奇异 Kerr 黑洞阴影更小、更扭曲。推断的圆度偏差ΔC≤0.10，对于M87*黑洞阴影，对非奇异Kerr-Sen黑洞参数（a，k）和（a，b）施加了约束。b=0.30M 和 k=0.30M 的最大阴影角直径分别为 θ _d =35.3461 μas 和 θ _d=35.3355 μas。我们还使用阴影可观测值估计与非奇异 Kerr-Sen 黑洞相关的参数。